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Digestion Part 2 Begins Thanks Mr. Tooth. Now to continue our journey out of the mouth. This is a detailed diagram of the next passage, the PHARYNX. BOLUS mixture of food and saliva ball that slides down the pharynx 3 REGIONS OF THE PHARYNX 1.Nasopharynx :above soft palate 2.Oropharynx from uvula down throat to hyoid bone. This is seen by the doctor with the tongue depressor 3.Laryngoppharynx: hyoid bone down to esophagus. EPIGLOTTIS: shuts the entrance to glottis - trachea (windpipe) Prevents choking It contains cartilage and is considered part of the voice-box — larynx. Choking occurs when the larynx is open when it should be closed and allows food or liquid into the windpipe. The larynx muscle relaxes when laughing – be careful when eating and joking around. Most people choke at the dinner table. Use the Heimlich manoeuvre if you have a choking victim. The food slides down the esophagus See if you can name the structures. 1 = esophagus 3. = stomach 2 = diaphragm 4.=liver Esophageal Hiatus Esophagus structure: Slippery mucus lining 25-30 cm length Smooth muscle Voluntary muscle 5.=gall bladder 8.= spleen 6.= duodenum 7.=pancreas PERISTALSIS ; wave like contraction of smooth muscle layers that pushes food through digestive tube -- esophagus to colon. Esophagus function: Conducts food into abdominal cavity PERISTALSIS Passes directly behind the heart Passes through the diaphragm via the esophageal hiatus and then into the stomach Next it enters me, the stomach. I produce gastric juice to digest the food. I hold the food in me for 2 to 6 hours and expand to about 2 L of food space. Food is trapped in me by the closed pyloric and cardiac sphincters Lower esophageal sphincter = cardiac sphincter Cardiac sphincter 3 muscle layers of stomach churn every 20s mixing the contents My gastric juice contains powerful digestive agents The following 3 come from my gastric pits I’m here to save the stomach lining Mucus cells- lubricate and protect the stomach lining cells from the powerful Acid - Enzyme combination. Making acid! HCl HCl – hydrochloric acid secreted by parietal cell Pepsinogen – inactive enzyme unless HCl is present turning it into Pepsin. Secreted by the Chief cells Make um good Pepsi (pepsin) You know, even with Captain Mucus, I have to completely replace the stomach lining every three days. Sometimes I don’t feel so good. You get an upset stomach because of too much acid. This acid activates pepin and the stomach starts to digest its inner membrane. esophagus This leads to ulcers – bleeding crater- like depressions Common in the stomach and duodenum Bleeding ulcer stiomach Small intestine Duodenal ulcer Stomach (peptic) ulcer You know, even with Captain Mucus, I have to completely replace the stomach lining every three days. That’s right and alcohol and aspirin tear my mucus protection away. So be careful how much you put in your stomach when acid is present without food. Hi there. I’m Mr Gall Bladder. Sometimes I release bile and it backflows into the stomach. Bile tears the mucus lining away as well and irritates the stomach lining. The stomach can start to bleed as a result. Sorry Hi there. Meet Helicobacter pylori, a member of my evil gang People underestimate me you know. Doctors now say that most stomach and duodenal ulcers are because of ME!! Helicobacter pylori That bacteria infection is the cause of most (80%) stomach and duodenal ulcers , Mr. Stomach. Take a look at an endoscope view of the inside of the stomach showing an ulceration. Ugly close up huh? Well I will prescribe you an antibiotic to kill off those Helicobacter pylori. That in combination with you watching your diet should fix your ulcer problem That looks terrible! Help me doc! Ha Ha I did that you know. I love acid! I grow well with more acid! Give me more acid all the time! GASTRIN makes more acid so make more Gastrin, dude. No not the antibiotics! I’m being destroyed. All my evilness, lost because the doctors found me out. AHHHHHHHH Sometimes, I need the acid reduced because it hurts when I eat spicy food. I usually take an antacid (Rolaids, Tums) or an acid blocker like Pepsid AC. These are good for temporary relief for occasional problems. Endoscope of a damaged esophageal lining I sometimes also have a problem with heartburn. It is caused when the acidic contents of the stomach gurgle up through the cardiac(lower esophageal) sphincter and contact the esophageal lining. This causes a burning sensation right behind my heart. The esophageal lining is damaged as a result of this happening often (chronic) This is ACID REFLUX DISEASE. Did you know? Some animals like the lamprey have no stomach at all. The esophagus feeds directly into the intestine. They are jawless fish and feed by attaching themselves to another fish with this sucker like mouth. Then they use their tongue like a rasp to scrape off tissue from the victim. Lampreys are related to some of the most primitive fish on the planet. (Makes sense – first fish were also jawless) Lamprey are an INVASIVE SPECIES from the ocean who are now infesting all the great lakes. They slipped into our system along with the locks that ocean freighters use to access the waterway. They are destroying large game-fish. The food remains in me until it liquefies and forms CHYME. It is then released through the pyloric sphincter into the duodenum. This is the first segment of the small intestine. The chyme is initially acidic, but it is neutralized by secretions by the pancreas in the duodenum. Hello there. I’m Mr. Pancreas and I produce a bicarbonate alkaline solution to neutralize the stomach acid. The small intestine cannot withstand acid like the stomach so this is priority #1. I also produce over 20 different digestive enzymes. Many such as trypsin and proteases are not activated until they contact another enzyme I produce called enterokinase or enteropeptidase NOTE: The pancreas performs double duty. It is both an exocrine gland secreting digestive chemicals into a duct, and an endocrine gland secreting hormones directly into the blood. (Glucagon and Insulin) Hi there Mr. Liver. What do you do here in the duodenum? I constantly release bile and store it in Mr. Gall Bladder. Bile is the waste product of red blood cell breakdown. That’s right. I store the bile. When you eat a fat containing meal, I squeeze the bile out to bile duct and into the duodenum. Bile is an emulsifier (detergent) that breaks fats into smaller droplets for easier digestion. I am the duodenum and when fats come through I release hormone CCR to cause Mr Gall Bladder is to release the bile. I also release hormone ENTEROGASTRONE to slow digestion to allow for the greater time needed to digest fats. CCR=cholecystokinin That ENTEROGASTRONE stuff makes me produce less acid and slows down peristalsis. That means you start to feel more full. Eat fat (cheese) slow digestionfeel full. I also produce the hormone SECRETIN that causes the pancreas to add its alkaline mixture. Right on!! I can’t do no secreting until I get the SECRETIN from you Mr. Duodenum Moving into the SMALL INTESTINE. MESENTARY is like cellophane, covering and preventing the intestine from kinks The purpose of the small intestine is primarily absorption , although some digestion will occur here. It is long and small in diameter in order to facilitate the movement of nutrients into the bloodstream . SURFACE AREA (100m2+) is ENHANCED with small finger like projections called VILLI and even smaller projections called MICROVILLI on the villi. Amino acids and sugars are absorbed and enter the blood vessel of the villus. Glycerol and fattl acids pass through the intestine wall and enter the LACTEAL. These fats are mixed with CHOLESTEROL and coated with PROTEINS to form GLOBS called CHYLOMICRONS Blood from the stomach small and large intestines that now contain lots of nutrients from the digested meal move into the hepatic vein. This vein goes to the LIVER. I always wondered what the HEPATIC PORTAL SYSTEM was about. Now I know. It’s just Mr Liver filtering through all the digested blood nutrients. HEPATIC=LIVER I will store much of the sugar and release it later. I will keep blood glucose relatively constant at about 90mg/100mL Everything you absorb from food must pass first through me! Ascending colon like ascending into heaven. Remember Jacob’s ladder? Undigested matter passes into the colon (large intestine) which is short but has a large diameter. It primarily absorbs the water back into the blood. Descending colon like descending into hell. Heard of Dante’s inferno? Abandon all hope all who enter. Transverse colon Ascending colon Descending colon caecum Sigmoid colon Appendix Rectum We are almost at the end of our journey. In the large intestine, large numbers of bacteria (E coli) are normal and they produce some vitamin K , biotin, folic acid and several B vitamins. These are absorbed and are useful for the body. Mr Badbacter. Get out of here. The colon is already full of us E coli I know I can’t get a foothold in this guy’s colon because of you. Why aren’t you bad like me? How come you’re helpin the guy like makin him vitamins? You know he’s just gonna flush you down the toilet He gives us food and a good home. That’s all we want. The remaining waste is stored in the rectum until eliminated from the body as feces. The bulk of the feces is actually bacteria. Why are feces(stools) always brown Mr. Genius? Remember the bile. Well the brown is from a combination of bile and bilirubin from the break down of red blood cell. The brown colour is normal. If you see black stools, however, that indicates that blood is being digested. You are probably leaking blood into the intestines, perhaps from an ulcer. Finally somthin’ evil is happenin’ Hey something serious is rumbling. I better get topside to see what is going on! What’s the problem here? Not me. It must be that enterkin-ASS duodenum producing too much- maybe ulcerating. I’m not producing to much enterokinase. Besides I’d just hurt myself as trypsin would tear away at my membrane. There is no ulcer you hepatic hypocrit. It’s not me either. Duodenum is making the secretin so I am adding enough base to the acid coming out of the stomach. Check out Mr Duo again. Maybe the problem is Enterogastrone Stop arguing guys. I’m the problem. When Mr. Duo sent the CCR I was blocked from releasing the bile. Sorry but I hurt. I feel OK . I’m was producing gastrin and making more acid but the guy is eating. That’s normal So I just added a little enterogastrone now . There was fat in the meal. It needs to slow down and I need the bile so I released CCR If you are blocked, that means we have a gall stone problem. I can feel the solidified cholesterol crystals at the entrance to the bile duct. They are causing a blockage every time I try to release bile. Gall stones will require surgery in your case. I will have to remove the stone and also Mr. Gall Bladder completely because he looks infected. It’s too bad they aren’t small stones because if they were we could smash them up with powerful ultrasonic waves in a non surgical setting. Those gall stones are very ugly inside you Mr. Gall Bladder. We have to stop releasing bile. That means no fats in meals right now! Remove me. I thought the body needed me. We are having gall stone attacks. The pain is really bad. You have to go. The body can get along without you. The liver will just drain the bile directly into the duodenum and bypass your storage system. You are lucky that the stones did not block the pancreatic duct as well. If this happens, pancreatitis develops. Jaundice( yellowing of skin or eyes) is also a serious affecting the liver. Call me right away if this or a fever develops. I’m essential. I’m also essential to survival. It’s better you go Mr.Gall Bladder than we all get destroyed resulting in death. Well that solves that problem. Wait a minute. What now? We have excruciating pain in our lower right abdomen. What is going on? You are experiencing an appendix attack. I will i I I I will remove it before it bursts. If it does, it will leak bacteria into the surrounding abdominal cavity leading to PERITONITIS a massive bacterial infection Well that’s all for today. Keep yourself healthy and eat properly. Digestion Ends